The father and two brothers of Manchester's suicide bomber have now been arrested, on suspicion of links to Islamic State.
All up, UK Police have confirmed 6 arrests - one of them was a man found carrying some kind of device, in the town of Wigan (27km west of Manchester City).
The arrests come after several properties, including one the suicide bomber had lived in.
At this stage, Manchester Police Chief Constable Ian Hopkins has confirmed it is "very clear" they're investigating what he called "a network".
It comes as we learn more about the bomb used in the attack -
Images of the device appear to show it was packed in a backpack, and appeared to be made up of tightly packed shrapnel.